Beverage dispenser coding devices are known in the art. U.S. Pat. No. 3,920,149 (Fortino et al.) describes a liquor bottle stopper and electromagnetic valve system which has three metal bands on the spout of the stopper whose presence can be detected by use of three detector coils, when the activator coil is energized. This system allows detection of up to seven different kinds of liquor.
In the prior art systems, it is difficult to efficiently detect a large number of different bottles.